Flexible substrate, method of manufacturing the same, and display apparatus employing the same

ABSTRACT

A flexible substrate includes a polymer substrate. At least a portion of a first barrier region is formed on a neutral plane of the polymer substrate. A top region is formed above the first barrier region. A bottom region is formed below the first barrier region. The first barrier region includes a first inorganic material disposed in at least a portion of a free volume of the polymer substrate. A density of the first inorganic material in the first barrier region is greater than a density of the first inorganic material in the top or bottom regions.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean PatentApplication No. 10-2016-0102439, filed on Aug. 11, 2016, in the KoreanIntellectual Property Office, the disclosure of which is incorporated byreference herein in its entirety.

1. TECHNICAL FIELD

Exemplary embodiments of the present invention relate to a flexiblesubstrate, and more particularly to a method of manufacturing theflexible substrate, and a display apparatus employing the flexiblesubstrate.

2. DISCUSSION OF RELATED ART

A display apparatus may display visual data. The display apparatus mayinclude a substrate including a display area and a non-display area. Inthe display area, a gate line and a data line may be electricallyseparated from each other and intersections between the gate lines andthe data lines may define a plurality of pixel areas in the displayarea. In the display area, a thin film transistor and a pixel electrodeelectrically connected thereto may be connected to respective pixelareas. In the non-display area, various conductive layers such as wirestransmitting electrical signals to the display area may be positioned.

A flexible display apparatus may include a bent portion or a reducedarea of a foldable non-display area. The flexible display apparatus mayinclude a flexible substrate including one or more polymer organicmaterials having relatively high mechanical flexibility and thermalresistance.

SUMMARY

One or more exemplary embodiments of the present invention provide aflexible substrate. The flexible substrate may be capable of reducing orpreventing an infiltration of outside air. One or more exemplaryembodiments of the present invention provide a method of manufacturingthe flexible substrate, and a display apparatus employing the flexiblesubstrate.

According to an exemplary embodiment of the present invention, aflexible substrate includes a polymer substrate. At least a portion of afirst barrier region is formed on a neutral plane of the polymersubstrate. A top region is formed above the first barrier region. Abottom region is formed below the first barrier region. The firstbarrier region includes a first inorganic material disposed in at leasta portion of a free volume of the polymer substrate. A density of thefirst inorganic material in the first barrier region is greater than adensity of the first inorganic material in the top or bottom regions.

According to an exemplary embodiment of the present invention, thedensity of the first inorganic material in the first barrier region maygradually decrease from a center thickness of the first barrier regiontoward upper and lower surfaces of the polymer substrate.

According to an exemplary embodiment of the present invention, the firstinorganic material may include at least one of silicon nitride, aluminumnitride, zirconium nitride, titanium nitride, hafnium nitride, tantalumnitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide,serium oxide, or silicon oxynitride (SiON).

According to an exemplary embodiment of the present invention, the firstinorganic material of the first barrier region may fill from about 0.1%to about 50% of a free volume of the first barrier region, and anaverage thickness of the first barrier region may be equal to or lessthan from about 5% to about 50% of a thickness of the polymer substrate.

According to an exemplary embodiment of the present invention, aposition of a basic core of the first barrier region need not coincidewith a position of the neutral plane.

According to an exemplary embodiment of the present invention, athickness of the polymer substrate may be from about 10 μm to about 100μm, and an average thickness of the first barrier region may be fromabout 50 nm to about 50 μm.

According to an exemplary embodiment of the present invention, theflexible substrate may include a second barrier region in at least oneof the top and bottom regions. The second barrier region includes asecond inorganic material disposed in at least a portion of the freevolume of the polymer substrate and a volume of the second barrierregion may be less than the volume of the first barrier region.

According to an exemplary embodiment of the present invention, thesecond inorganic material may be the same as the first inorganicmaterial.

According to an exemplary embodiment of the present invention, ahardness of the first barrier region is greater than a hardness of thetop and bottom regions.

According to an exemplary embodiment of the present invention, a methodof manufacturing a flexible substrate includes injecting a firstreactant above a polymer substrate into a top surface of the polymersubstrate and infiltrating the first reactant into the polymersubstrate. The method includes injecting a second reactant below thepolymer substrate into a bottom surface of the polymer substrate andinfiltrating the second reactant into the polymer substrate. The methodincludes forming a barrier region by filling at least a portion of afree volume of the polymer substrate with an inorganic material formedvia a reaction of the first and second reactants inside the polymersubstrate.

According to an exemplary embodiment of the present invention, themethod may includes, after forming the barrier region, identifyingwhether at least one of the first and second reactants has penetratedinto the polymer substrate.

According to an exemplary embodiment of the present invention, in theinfiltrating of the first reactant, a pressure above the polymersubstrate may be greater than a pressure below the polymer substrate.

According to an exemplary embodiment of the present invention, in theinfiltrating of the second reactant, a pressure above the polymersubstrate may be less than a pressure below the polymer substrate.

According to an exemplary embodiment of the present invention, theinfiltrating of the first reactant and the infiltrating of the secondreactant may be sequentially performed.

According to an exemplary embodiment of the present invention, the firstreactant may be one of water (H₂O), ozone (O₃), or ammonia (NH₃).

According to an exemplary embodiment of the present invention, theinorganic material formed via the reaction of the first and secondreactants may include at least one of silicon nitride, aluminum nitride,zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride,silicon oxide, aluminum oxide, titanium oxide, tin oxide, serium oxide,or SiON.

According to an exemplary embodiment of the present invention, at leasta portion of the barrier region may be placed on a neutral plane of thepolymer substrate.

According to an exemplary embodiment of the present invention amanufacturing apparatus may be configured to manufacture the flexiblesubstrate. The apparatus may include a first serve chamber and a secondserve chamber. The polymer substrate may be disposed between side wallsof the first and second serve chambers. The polymer substrate may forman airtight seal in the first and second chambers. The first servechamber may include a first gas supplier configured to supply the firstreactant, a first residual gas analyzer, and a first temperaturecontroller, and the second serve chamber may include a second gassupplier configured to supply the second reactant, a second residual gasanalyzer, and a second temperature controller.

According to an exemplary embodiment of the present invention, a methodof manufacturing a flexible substrate includes infiltrating a firstreactant into substantially an entire polymer substrate; and removingthe first reactant infiltrated into a top region in the polymersubstrate. The method includes infiltrating a second reactant into atleast a portion of the polymer substrate; and forming a barrier regionby filling at least a portion of a free volume of the polymer substratewith an inorganic material formed via a reaction of the first and secondreactants inside the polymer substrate.

According to an exemplary embodiment of the present invention, theinfiltrating of the first reactant may be performed after the polymersubstrate was placed in an oven including the first reactant.

According to an exemplary embodiment of the present invention, theremoving of the first reactant may be performed by applying heat to atop surface of the polymer substrate and diffusing the first reactant tooutside the polymer substrate.

According to an exemplary embodiment of the present invention, theinfiltrating of the second reactant may be performed inside a vacuumchamber device.

According to an exemplary embodiment of the present invention, the firstreactant is one of H₂O, 0 ₃, or NH₃.

According to an exemplary embodiment of the present invention, theinorganic material formed via the reaction of the first and secondreactants may include at least one of silicon nitride, aluminum nitride,zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride,silicon oxide, aluminum oxide, titanium oxide, tin oxide, serium oxide,or SiON.

According to an exemplary embodiment of the present invention, at leasta portion of the barrier region may be placed on a neutral plane of thepolymer substrate.

According to an exemplary embodiment of the present invention, after theforming of the barrier regions, identifying may be further includedwhether at least one of the first and second reactants penetratedthrough the polymer substrate.

According to an exemplary embodiment of the present invention, a displayapparatus includes a flexible substrate including a display area and anon-display area. A display device is in the display area and a thinfilm transistor is connected to the display device. An encapsulationlayer is configured to encapsulate the display area. The flexiblesubstrate includes a polymer substrate and a first barrier region. Atleast a portion of the first barrier region is formed on a neutral planeof the polymer substrate. A top region is formed above the first barrierregion, and a bottom region is formed below the first barrier region.The first barrier region includes a first inorganic material disposed inat least a portion of a free volume of the polymer substrate. A densityof the first inorganic material in the first barrier region is greaterthan a density of the first inorganic material in the top or bottomregions.

According to an exemplary embodiment of the present invention, thenon-display area of the flexible substrate may include a bending areabent around a bending axis. The display apparatus may include a fan-outwire with at least a portion of the fan-out wire in the bending area.The display apparatus may include an organic material layer with atleast a portion or the organic material layer between the fan-out wireand the flexible substrate in the bending area.

According to an exemplary embodiment of the present invention, thedisplay apparatus may include an inorganic insulating layer on theflexible substrate, the inorganic insulating layer having an openingcorresponding to the bending area. The organic material layer may fillat least a portion of the opening.

According to an exemplary embodiment of the present invention, thedisplay device may be an organic light-emitting diode including a pixelelectrode, a counter electrode facing the pixel electrode, and anintermediate layer including an organic light-emitting layer between thepixel electrode and the counter electrode.

According to an exemplary embodiment of the present invention, a densityof the first inorganic material in the first barrier region graduallymay decrease from a center thickness of the first barrier region towardupper and lower ends of the flexible substrate.

According to an exemplary embodiment of the present invention, athickness of the top region may be different from a thickness of thebottom region.

According to an exemplary embodiment of the present invention, thedisplay apparatus may include a second barrier region in at least one ofthe top and bottom regions. The second barrier region includes a secondinorganic material disposed in at least a portion of the free volume ofthe polymer substrate. A volume of the second barrier region may be lessthan a volume of the first barrier region.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become moreapparent by describing in detail exemplary embodiments thereof, withreference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a flexible substrate according to anexemplary embodiment of the present invention;

FIG. 2 is an enlarged view of a portion A in FIG. 1;

FIG. 3 is a diagram illustrating a neutral plane and strain duringbending;

FIG. 4 is a cross-sectional view of a flexible substrate according to anexemplary embodiment of the present invention;

FIG. 5 is a flowchart of a method of manufacturing a flexible substrateaccording to an exemplary embodiment of the present invention;

FIG. 6 is a cross-sectional view of a manufacturing device forimplementing the method of manufacturing of FIG. 5;

FIG. 7 is a flowchart of a method of manufacturing a flexible substrateaccording to an exemplary embodiment of the present invention;

FIG. 8A is a diagram illustrating a method of manufacturing a flexiblesubstrate according to an exemplary embodiment of the present invention;

FIG. 8B is a diagram illustrating a method of manufacturing a flexiblesubstrate according to an exemplary embodiment of the present invention;

FIG. 8C is a diagram illustrating a method of manufacturing a flexiblesubstrate according to an exemplary embodiment of the present invention;

FIG. 8D is a diagram illustrating a method of manufacturing a flexiblesubstrate according to an exemplary embodiment of the present invention;

FIG. 8E is a diagram illustrating a method of manufacturing a flexiblesubstrate according to an exemplary embodiment of the present invention;

FIG. 9 is a perspective view of a portion of a display apparatusaccording to an exemplary embodiment of the present invention; and

FIG. 10 is a cross-sectional view of a portion of the display apparatusof FIG. 9.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention will be described belowin more detail with reference to the accompanying drawings. In thisregard, the exemplary embodiments may have different forms and shouldnot be construed as being limited to the exemplary embodiments of thepresent invention described herein.

Like reference numerals may refer to like elements throughout thespecification and drawings. It will be understood that although theterms “first” and “second” may be used herein to describe variouscomponents, these components should not be limited by these terms. Sizesof elements in the drawings may be exaggerated for clarity ofdescription.

Sizes of elements in the drawings may be exaggerated for clarity ofdescription.

According to some exemplary embodiments of the present invention, thex-axis, the y-axis and the z-axis are not limited to three axes of therectangular coordinate system, and may be interpreted in a broadersense. For example, the x-axis, the y-axis, and the z-axis may beperpendicular to one another, or may represent different directions thatare not perpendicular to one another.

When an exemplary embodiment of the present invention may be implementeddifferently, a specific process order may be performed differently fromthe described order.

FIG. 1 is a cross-sectional view of a flexible substrate according to anexemplary embodiment of the present invention. FIG. 2 is an enlargedview of a portion A in FIG. 1. FIG. 3 is a diagram illustrating aneutral plane and strain during bending.

Referring to FIGS. 1 through 3, a flexible substrate 100 according to anexemplary embodiment of the present invention may include a polymersubstrate 101. A first barrier region 103 with at least a portionthereof may be on a neutral plane NP of the polymer substrate 101. A topregion 101 a of the polymer substrate 101 may be above the first barrierregion 103, and a bottom region 101 b of the polymer substrate 101 maybe below the first barrier region 103.

The first barrier region 103 may include a first inorganic material 51filling at least a portion of a free volume of the polymer substrate101. A density of the first inorganic material 51 of the first barrierregion 103 may be greater than that of the first inorganic material 51of the top region 101 a and/or the bottom region 101 b. The firstinorganic material 51 need not be included in the top region 101 aand/or the bottom region 101 b, and even when the first inorganicmaterial 51 is included in the top region 101 a and/or the bottom region101 b, an amount of the first inorganic material 51 included in the topregion 101 a and/or the bottom region 101 b may be less than that of thefirst inorganic material 51 included in the first barrier region 103.

As an example, the flexible substrate 100 may include the firstinorganic material 51 filling a free volume 50 of the polymer substrate101, and the density of the first inorganic material 51 may be greaternear the neutral plane NP than near upper and lower surfaces of thepolymer substrate 101.

The polymer substrate 101 may include one or more polymer materialshaving a flexible or bendable property. According to an exemplaryembodiment of the present invention, the polymer substrate 101 mayinclude at least one polymer organic material, such as acrylate resin,methacrylate resin, polyisoprene, vinyl resin, urethane resin,cellulosic resin, or perylene resin. As an example, the polymersubstrate 101 may include, for example, polymer resin such aspolyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI),polyethylene naphthalate (PEN), polyethylene terephthalate (PET),polyphenylene sulfide (PPS), polyallylate, polyimide (PI), polycarbonate(PC), or cellulose acetate propionate (CAP).

The polymer substrate 101 may include polymer chains and the free volume50, which may be a space not occupied by polymer molecules betweenpolymer chains. As an example, the free volume 50 may refer to asubstantially empty space formed between polymer chains.

The polymer substrate 101 may be more flexible as a volume of the freevolume 50 becomes larger. However, the free volume 50 may be a paththrough which moisture or oxygen from the outside may infiltrate. In anexemplary embodiment of the present invention, the first inorganicmaterial 51 with a relatively high concentration may be formed in thefirst barrier region 103. Thus, an overall flexibility of the flexiblesubstrate 100 may be secured while an occurrence of moisture or oxygenpassing through the flexible substrate 100 is reduced or prevented.

The first inorganic material 51 may substantially fill the free volume50 of the polymer substrate 101 and thus block the path through whichmoisture or oxygen from the outside infiltrates into the free volume 50.

When first barrier region 103 includes relatively more of the firstinorganic material 51 than the top and bottom regions 101 a and 101 b,the first barrier region 103 may have a relatively higher hardness thanthat of the top region 101 a and the bottom region 101 b. When the firstinorganic material 51 is substantially uniformly positioned throughoutthe entire area of the polymer substrate 101, an overall hardness of theflexible substrate 100 may increase due to the first inorganic material51, and thus, the flexibility of the flexible substrate 100 may bereduced.

Thus, forming the first barrier region 103 to have a relatively smallthickness may increase a flexibility of the flexible substrate 100. Whenthe first inorganic material 51 fills a portion of the free volume 50 ofthe first barrier region 103, the path of moisture or gas (e.g., oxygen)may be blocked. According to an exemplary embodiment of the presentinvention, the first inorganic material 51 of the first barrier region103 may fill from about 0.1% to about 50% of the free volume 50 of thefirst barrier region 103, and an average thickness t of the firstbarrier region 103 may be from about 5% to about 50% of a thickness T ofthe flexible substrate 100. According to an exemplary embodiment of thepresent invention, the thickness t of the first barrier region 103 maybe less than a thickness of the top region 101 a or the bottom region101 b.

According to an exemplary embodiment of the present invention, thethickness T of the flexible substrate 100 may be from about 10 μm toabout 100 μm. According to an exemplary embodiment of the presentinvention, the thickness t of the first barrier region 103 may be fromabout 50 nm to about 50 μm.

The first barrier region 103 may have at least a portion thereof in theneutral plane NP of the polymer substrate 101. Thus, an occurrence of acrack in the first barrier region 103 when the flexible substrate 100bends may be reduced or prevented.

According to an exemplary embodiment of the present invention, theneutral plane NP may refer to a surface formed inside an object when theobject is being bent, the object neither stretching nor shrinking alongthis surface so that the original length of the object remainssubstantially constant. As an example, the neutral plane NP may refer toa surface not affected by elongation or compression, and thus, thestrain thereof may be zero. Thus, when the first barrier region 103 isformed on the neutral plane NP, little or no strain might occur at atime of bending the flexible substrate 100, and a probability of a crackoccurrence in the first inorganic material 51 filling the free volume 50may be reduced or eliminated. However, strain due to bending mayincrease toward a surface of the object, and when an inorganic materialwith a relatively high hardness is positioned on the surface of theobject, the probability of the crack occurrence may increase at the timeof bending.

In an exemplary embodiment of the present invention, at least a portionof the first barrier region 103 may be on the neutral plane NP of thepolymer substrate 101. The first barrier region 103 may be on theneutral plane NP, but a basic core Bc of the first barrier region 103along a direction of the thickness t need not coincide with the neutralplane NP. As an example, a thickness of the top region 101 a and athickness of the bottom region 101 b may be different from each other.

In an exemplary embodiment of the present invention, the first barrierregion 103 may be separated from upper and lower surfaces of the polymersubstrate 101. At least a portion of the first barrier region 103 may beon the neutral plane NP of the polymer substrate 101. Thus, theflexibility of the flexible substrate 100 may be secured and the pathfor infiltration from the outside air may be blocked by preventing orreducing the crack occurrence in the first barrier region 103.

According to an exemplary embodiment of the present invention, thedensity of the first barrier region 103 may be relatively highest in thebasic core Bc of the thickness T of the first barrier region 103 and maygradually decrease along directions toward upper and lower surfaces ofthe flexible substrate 100. In a method of manufacturing the firstbarrier region 103 according to an exemplary embodiment of the presentinvention, a reaction of reactants forming the first inorganic material51 may occur at a relatively high rate in the basic core Bc of thethickness t of the first barrier region 103.

The first inorganic material may include at least one of siliconnitride, aluminum nitride, zirconium nitride, titanium nitride, hafniumnitride, tantalum nitride, silicon oxide, aluminum oxide, titaniumoxide, tin oxide, serium oxide, or silicon oxynitride (SiON).

FIG. 4 is a cross-sectional view of a flexible substrate according to anexemplary embodiment of the present invention. Like reference numbersdenote like components in FIG. 4, as in FIG. 1, and duplicatedescriptions will be omitted for the sake of simplicity.

Referring to FIG. 4, a flexible substrate 100′ may include the polymersubstrate 101 and the first barrier region 103 with a portion thereof onthe neutral plane NP of the polymer substrate 101. The first barrierregion 103 may include the first inorganic material 51 filling at leasta portion of the free volume 50 of the polymer substrate 101. Thedensity of the first inorganic material 51 included in the first barrierregion 103 may be relatively higher than that of the first inorganicmaterial 51 included in the top and bottom regions 101 a and 101 b.

The flexible substrate 100′ may include a second barrier region 105 inat least one of the top region 101 a and the bottom region 101 b inaddition to the first barrier region 103. The second barrier region 105may include a second inorganic material filling at least a portion of afree volume of the second barrier region 105. A volume of the secondbarrier region 105 may be less than that of the first barrier region103.

The second barrier region 105 may be separated from the first barrierregion 103 and may be formed when the first barrier region 103 isformed. However, exemplary embodiments of the present invention are notlimited thereto. The second barrier region 105 may be formed via aseparate process after the first barrier region 103 has been formed.

The second barrier region 105 may be formed relatively closer to upperand lower surfaces of the polymer substrate 101 with respect to thefirst barrier region 103. The second inorganic material included in thesecond barrier region 105 may have a higher risk of the crack occurrencethan the first inorganic material 51 of the first barrier region 103 atthe time of bending the flexible substrate 100′. However, even when thecrack may occur in the second barrier region 105, the flexible substrate100′ may have an infiltration path of outside air that is blocked by thefirst barrier region 103.

The second inorganic material may include the same material or materialsas the first inorganic material 51 included in the first barrier region103, or the second inorganic material may include at least one materialthat is different from the first inorganic material 51.

The second inorganic material may include at least one of siliconnitride, aluminum nitride, zirconium nitride, titanium nitride, hafniumnitride, tantalum nitride, silicon oxide, aluminum oxide, titaniumoxide, tin oxide, serium oxide, or SiON.

At least a portion of the first barrier region 103 may be on the neutralplane NP of the polymer substrate 101. The first barrier region 103 maybe on the neutral plane NP, but the basic core Bc along a thicknessdirection of the first barrier region 103 need not coincide with theneutral plane NP. As an example, a thickness of the top region 101a maybe different from that of the bottom region 101 b. Depth of the basiccore Bc from a surface of the polymer substrate 101 may be from about 5μm to about 50 μm.

The flexible substrates 100 and 100′ according to an exemplaryembodiment of the present invention may include the first barrier region103 with at least a portion thereof on the neutral plane NP of thepolymer substrate 101, and thus, the infiltration path of the outsideair may be blocked while the flexibility of the flexible substrates 100and 100′ may be maintained.

FIG. 5 is a flowchart of a method of manufacturing a flexible substrateaccording to an exemplary embodiment of the present invention. FIG. 6 isa cross-sectional view of a manufacturing apparatus using the method ofmanufacturing of FIG. 5.

Referring to FIGS. 5 and 6, the method of manufacturing the flexiblesubstrates 100 and 100′ may include infiltrating a first reactant 41into the polymer substrate 101 from above the top surface of the polymersubstrate 101 (S1). The method of manufacturing the flexible substrates100 and 100′ may include infiltrating a second reactant 42 into thepolymer substrate 101 from below the bottom surface of the polymersubstrate 101 (S2). The method of manufacturing the flexible substrates100 and 100′ may include forming a barrier region (e.g., the firstbarrier region 103) inside the polymer substrate 101. The barrierregions may fill the free volume of the polymer substrate 101 with thefirst inorganic material 51 formed via a reaction between the firstreactant 41 and the second reactant 42 (S3). The method of manufacturingthe flexible substrates 100 and 100′ may include identifying whethereither the first reactant 41 or the second reactant 42 has penetratedthrough the polymer substrate 101 (S4).

Referring to FIG. 6, the manufacturing apparatus according to anexemplary embodiment of the present invention may include a first servechamber SC1 and a second serve chamber SC2. The polymer substrate 101may be disposed between the first serve chamber SC1 and the second servechamber SC2. The polymer substrate 101 may form an airtight seal in eachof the first serve chamber SC1 and the second serve chamber SC2. Thefirst serve chamber SC1 may be a chamber configured to supply the firstreactant 41 to the polymer substrate 101 through a first gas supplierG1. The second serve chamber SC2 may be a chamber configured to supplythe second reactant 42 to the polymer substrate 101 through a second gassupplier G2.

The first and second serve chambers SC1 and SC2 may be vacuum chambers,and pressure inside the first and second serve chambers SC1 and SC2 maybe lowered to equal to or less than about 10⁻⁶ Torr.

The first and second serve chambers SC1 and SC2 may respectively includea first temperature controller TC1 and a second temperature controllerTC2. The first and second temperature controllers TC1 and TC2 may be hotwire type temperature controllers. The first and second temperaturecontrollers TC1 and TC2 may be positioned inside the first and secondserve chambers SC1 and SC2, respectively, and may control temperatureinside chambers via radiation heat.

The first and second serve chambers SC1 and SC2 may respectively includea first residual gas analyzer RGA1 and a second residual gas analyzerRGA2 for identifying whether either the first reactant 41 or the secondreactant 42 is detected.

Each of the first and second serve chambers SC1 and SC2 may include atleast one exhaust unit. Each of the exhaust units may be configured toexhaust gas from the first or second serve chambers SC1 and SC2.

A sealing member may be disposed between a side wall of each of thefirst and second serve chambers SC1 and SC2 and the polymer substrate101. The sealing members may seal the first and second serve chambersSC1 and SC2, respectively.

A process of forming a flexible substrate will be described in moredetail below with reference to FIG. 5 and FIG. 6. The manufacturingapparatus described with reference to FIG. 6 is an exemplary apparatus;however exemplary embodiments of the present invention are not limitedthereto.

The polymer substrate 101 may be positioned between the first and secondserve chambers SC1 and SC2, and the pressure inside the first and secondserve chambers SC1 and SC2 may be maintained at equal to or less thanabout 10 ⁻² Torr. Viewed from above, since an area of the polymersubstrate 101 is larger than areas of the first and second servechambers SC1 and SC2, a closed space may be formed by the first andsecond serve chambers SC1 and SC2, and the polymer substrate 101. Thepolymer substrate 101 may be provided in a roll-to-roll shape. However,exemplary embodiments of the present invention are not limited thereto.

The first reactant 41 may infiltrate into the polymer substrate 101 fromabove the polymer substrate 101. The first reactant 41 may be injectedinto the first serve chamber SC1 through the first gas supplier G1.Thus, the pressure in the first serve chamber SC1 may become higher thanthat in the second serve chamber SC2. As an example, the pressure abovethe polymer substrate 101 may become higher than that below the polymersubstrate 101. The first reactant 41 may diffuse into the polymersubstrate 101 due to a pressure difference between above and below thepolymer substrate 101. As an example, the first reactant 41 mayinfiltrate into the inside of the polymer substrate 101 through the topsurface of the polymer substrate 101 and at least up to the neutralplane NP of the polymer substrate 101. According to an exemplaryembodiment of the present invention, when the first reactant 41 isinjected into the first serve chamber SC1, an inside pressure of thefirst serve chamber SC1 may be from about 10⁻² Torr to about 1 Torr, andan inside pressure of the second serve chamber SC2 may be from about10⁻⁶ Torr to about 10⁻² Torr.

The second reactant 42 may infiltrate into the polymer substrate 101from below the polymer substrate 101. The second reactant 42 may beinjected into the second serve chamber SC2 through the second gassupplier G2. The second reactant 42 may diffuse into the polymersubstrate 101 by controlling the pressure in the second serve chamberSC2 to be higher than that in the first serve chamber SC1. As anexample, the pressure above the polymer substrate 101 may be controlledto be lower than that below the polymer substrate 101. According to anexemplary embodiment of the present invention, when the second reactant42 is injected into the second serve chamber SC2, the inside pressure ofthe first serve chamber SC1 may be from about 10⁻⁶ Torr to about 10⁻²Torr, and that of the second serve chamber SC2 may be from about 10⁻²Torr to about 1 Torr. The pressure in the first serve chamber SC1 may becontrolled such that the first reactant 41 is positioned near theneutral plane NP of the polymer substrate 101. The second reactant 42may infiltrate into the inside of the polymer substrate 101 through thebottom surface of the polymer substrate 101 and at least up to theneutral plane NP of the polymer substrate 101.

The first reactant 41 may include a gas forming the inorganic materialvia a reaction with the second reactant 42 and need not be limited to aparticular material. For example, the first reactant 41 may use water(H₂O), ozone (O₃), ammonia (NH₃), oxygen (O₂), hydrogen (H₂), or air.According to an exemplary embodiment of the present invention, the firstreactant 41 may be H₂O. In the case of H₂O, since absorption of H₂O intothe polymer substrate 101 may occur, a removal of H₂O from the polymersubstrate 101 may be performed. According to an exemplary embodiment ofthe present invention, H₂O may be used as the first reactant 41 to reactwith the second reactant 42 and the removal of H₂O from the polymersubstrate 101 may be substantially simultaneously performed withformation of the first barrier region 103.

The second reactant 42 may be a gas forming the inorganic material via areaction with the first reactant 41 and need not be limited to aparticular material. For example, second reactant 42 may includetetrakis(dimethylamino)silane (TDMAS), tetrakis(ethylmethylamino)silane(TEMASi), tris(ethlymethylamino)silane (Tris-EMAS),tris(dimethylamino)silane (Tris-DMAS), tetraethyl orthosilicate (TEOS),bis(ethylmethylamino)silane (BEMAS), bis(diethylamino)silane (BDEAS),trimethylaluminum (TMA), tris(tertiary-butyl) aluminum (TTBA),tetrakis(ethylmethylamino)zirconium (TEMAZ), titanium tetrachloride(TiCl₄), tetrakis(dimethylamino)titanium (TDMAT),tetrakis(ethylmethylamino)titanium (TEMAT),tetrakis(diethylamino)titanium (TDEAT), titanium tetraisopropoxide(TTIP), tertiary-butyl-imido tri(diethylamino)tantalum (TBTDET),tetrakis(ethylmethylamino)hafnium (TEMAH), tertiary-butyl-imidotris(ethylmethylamino) tantalum (TBITEMATa), polyethylene terephthalate(PET), strontium (2,2,6,6-tetramethyl-3,5-heptanedionate)₂ (Sr(thd)₂),or tetrakis(ethylmethylamino) antimony (TEMASb).

The injecting of the first reactant 41 and the injecting of the secondreactant and 42 may be sequentially performed. However, exemplaryembodiments of the present invention are not limited thereto. Theinjections of the first and second reactants 41 and 42 may besubstantially simultaneously performed.

The first and second reactants 41 and 42 may infiltrate into the insideof the polymer substrate 101, react with each other near the neutralplane NP of the polymer substrate 101, and form the first inorganicmaterial 51. The first inorganic material 51 may fill the free volume 50of the polymer substrate 101 and form the first barrier region 103. Adesired temperature for the reaction of the first and second reactants41 and 42 may be respectively provided via the first and secondtemperature controllers TC1 and TC2 inside the corresponding chambers.

The first inorganic material 51 may include at least one of siliconnitride, aluminum nitride, zirconium nitride, titanium nitride, hafniumnitride, tantalum nitride, silicon oxide, aluminum oxide, titaniumoxide, tin oxide, serium oxide, or SiON.

Since the first and second reactants 41 and 42 may react with each othernear the neutral plane NP of the polymer substrate 101, at least aportion of the first barrier region 103 may be on the neutral plane NPof the polymer substrate 101.

The density of the first inorganic material 51 may decrease from acenter thickness of the first barrier region 103 toward upper and lowersurfaces of the polymer substrate 101.

When the first barrier region 103 is formed, the second barrier region105 separated from the first barrier region 103 may also be formed, buta volume of the second barrier region 105 may be less than that of thefirst barrier region 103.

While the first reactant 41 is injected into the first serve chamberSC1, whether the first reactant 41 has been detected in the second servechamber SC2 may be identified. This operation may be performed by thesecond residual gas analyzer RGA2. As an example, formation of barrierregions inside the polymer substrate 101 may be identified by detectingnone of the first reactant 41 in the second serve chamber SC2. As anexample, formation of barrier regions may be identified by detectingnone of the second reactant 42 in the first serve chamber SC1 while thesecond reactant 42 is injected into the second serve chamber SC2.

Since the first and second serve chambers SC1 and SC2 may be separatedfrom each other via the polymer substrate 101, only one reactant may besupplied to respective serve chambers SC1 and SC2. Thus, contaminationinside the first and second serve chambers SC1 and SC2 may be reduced oreliminated and formation of the first barrier region 103 may beidentified substantially immediately by the residual gas analyzers RGA1and RGA2.

FIG. 7 is a flowchart of a method of manufacturing a flexible substrateaccording to an exemplary embodiment of the present invention. FIGS. 8Ato 8E are diagrams illustrating a method of manufacturing a flexiblesubstrate according to an exemplary embodiment of the present invention.

Referring to FIG. 7, a method of manufacturing the flexible substratemay include infiltrating the first reactant 41 into an entire portion ofthe polymer substrate 101 (SS1). The method of manufacturing theflexible substrate may include removing a portion of the first reactant41 from inside the polymer substrate 101 (SS2). The method ofmanufacturing the flexible substrate may include infiltrating the secondreactant 42 into a portion of the polymer substrate 101 (SS3). Themethod of manufacturing the flexible substrate may include forming thefirst barrier region 103 inside the polymer substrate 101 (SS4). Themethod of manufacturing the flexible substrate may include identifyingwhether the first reactant 41 was detected (SS5).

Referring to FIG. 8A, the polymer substrate 101 may be on a carriersubstrate CS. The carrier substrate CS may be, for example, a glasssubstrate. The carrier substrate CS may have sufficient hardness toprevent the flexible polymer substrate 101 from being bent or deformedduring a manufacturing process.

Referring to FIG. 8B, the polymer substrate 101 may be exposed to anenvironment having the first reactant 41 in a relatively highconcentration and the first reactant 41 may infiltrate intosubstantially the entire polymer substrate 101. The first reactant 41may include a material forming an inorganic material via a reaction withthe second reactant 42 and the first reactant 41 need not be limited toa particular material. For example, the first reactant 41 may includeH₂O, O₃, or NH₃.

According to an exemplary embodiment of the present invention, the firstreactant 41 may include a liquid such as the water (H₂O). In this case,for infiltrating the first reactant 41 into substantially the entirepolymer substrate 101, a method of immersion of the polymer substrate101 in a liquid such as the water may allow the first reactant 41 todiffuse into substantially the entire polymer substrate 101.

According to an exemplary embodiment of the present invention, the firstreactant 41 may be a gas. In this case, for infiltrating the firstreactant 41 into substantially the entire portion of the polymersubstrate 101, the polymer substrate 101 may be placed in a vessel suchas an oven having the first reactant 41 in a relatively highconcentration.

The first reactant 41 may be injected from above the polymer substrate101 and allowed to diffuse after the polymer substrate 101. The polymersubstrate 101 may be positioned in a vacuum chamber maintaining acertain pressure for infiltrating the first reactant 41 into the polymersubstrate 101. Thus, it may take a relatively long amount of time forthe first reactant 41 to diffuse into substantially the entire polymersubstrate 101. Thus, when a traditional atomic layer deposition (ALD)equipment or chemical vapor deposition (CVD) equipment is used forinfiltrating the first reactant 41 into the polymer substrate 101, acost and an amount of time for diffusing the first reactant 41 into thepolymer substrate may be relatively high.

However, an exemplary embodiment of the present invention, since thepolymer substrate 101 is positioned in a vessel with the first reactant41 in a relatively high concentration, separate vacuum equipment mightnot be used and thus, manufacturing time and cost may be reduced. Aplurality of polymer substrates 101 can be simultaneously placed in avessel having the first reactant 41 in a relatively high concentration,thus increasing efficiency in terms of cost and time for diffusing thefirst reactant 41 into the polymer substrate.

Referring to FIG. 8C, a portion of the first reactant 41 may be removedby applying heat. For example, heat may be applied from above thepolymer substrate 101. When heat is applied from above the polymersubstrate 101, the first reactant 41 which was diffused near the topsurface of the polymer substrate 101 may escape from the polymersubstrate 101, while the first reactant 41 which was diffused near thebottom surface (e.g., near the carrier substrate CS) may remain.

Referring to FIG. 8D, the polymer substrate 101 may then be exposed tothe second reactant 42. The second reactant 42 may be a material formingthe inorganic material via a reaction with the first reactant 41 andneed not be limited to a particular material. For example, secondreactant 42 may include tetrakis(dimethylamino)silane (TDMAS),tetrakis(ethylmethylamino)silane (TEMASi), tris(ethlymethylamino)silane(Tris-EMAS), tris(dimethylamino)silane (Tris-DMAS), tetraethylorthosilicate (TEOS), bis(ethylmethylamino)silane (BEMAS),bis(diethylamino)silane (BDEAS), trimethylaluminum (TMA),tris(tertiary-butyl) aluminum (TTBA),tetrakis(ethylmethylamino)zirconium (TEMAZ), titanium tetrachloride(TiCl₄), tetrakis(dimethylamino)titanium (TDMAT),tetrakis(ethylmethylamino)titanium (TEMAT),tetrakis(diethylamino)titanium (TDEAT), titanium tetraisopropoxide(TTIP), tertiary-butyl-imido tri(diethylamino)tantalum (TBTDET),tetrakis(ethylmethylamino)hafnium (TEMAH), tertiary-butyl-imidotris(ethylmethylamino) tantalum (TBITEMATa), polyethylene terephthalate(PET), strontium (2,2,6,6-tetramethyl-3,5-heptanedionate)₂ (Sr(thd)₂),or tetrakis(ethylmethylamino) antimony (TEMASb).

The polymer substrate 101 may be positioned in a vessel having thesecond reactant 42 in a relatively high concentration for infiltratingthe second reactant 42 into substantially the entire polymer substrate101. Since the bottom surface of the polymer substrate 101 may becovered by the carrier substrate CS, the second reactant 42 may diffuseinto the inside of the polymer substrate 101 mainly through the topsurface of the polymer substrate 101. According to an exemplaryembodiment of the present invention, vacuum chamber equipment may beused to infiltrate the second reactant 42 into the polymer substrate101. Diffusion of the second reactant 42 in substantially the entirepolymer substrate 101 may be omitted. As an example, the second reactant42 may be diffused only to near the neutral plane NP of the polymersubstrate 101 to react with the first reactant 41 using vacuum chamberequipment. Thus, use of vacuum chamber equipment for diffusion of thesecond reactant 42 need not be disadvantageous with respect toprocessing time. A fact that the vacuum chamber equipment is used mayillustrate that only the second reactant 42 is injected to react withthe first reactant 41 after the polymer substrate 101 was maintained ina vacuum state before injecting the second reactant 42. Thus, since thefirst reactant 41 becomes subject to a relatively low pressure in thevacuum chamber after having infiltrated down to the bottom surface ofthe polymer substrate 101, the first reactant 41 may easily diffuse nearthe neutral plane NP of the polymer substrate 101. Thus, an infiltrationof other materials than the second reactant 42 may be reduced orprevented.

The pressure inside the vacuum chamber may increase while the secondreactant 42 is injected. When the second reactant 42 is exposed to thepolymer substrate 101 the second reactant 42 may diffuse toward theneutral plane NP from above the polymer substrate 101, and the firstreactant 41 near the bottom surface of the polymer substrate 101 maydiffuse toward the top surface of the polymer substrate 101. Thus, thefirst and second reactants 41 and 42 may react with each other near theneutral plane NP of the polymer substrate 101 to form the firstinorganic material 51. The first inorganic material 51 may fill the freevolume 50 of the polymer substrate 101 and may form the first barrierregion 103, and thus, the flexible substrate 100 may be formed.

The first inorganic material 51 may include at least one of siliconnitride, aluminum nitride, zirconium nitride, titanium nitride, hafniumnitride, tantalum nitride, silicon oxide, aluminum oxide, titaniumoxide, tin oxide, serium oxide, or SiON.

Since the first and second reactants 41 and 42 react with each othernear the neutral plane NP of the polymer substrate 101, at least aportion of the first barrier region 103 may be near the neutral plane NPof the polymer substrate 101.

The density of the first inorganic material 51 may decrease from thecenter thickness of the first barrier region 103 toward upper and lowersurfaces of the polymer substrate 101.

When the first barrier region 103 is formed, the second barrier region105 separated from the first barrier region 103 may also be formed, buta volume of the second barrier region 105 may be less than that of thefirst barrier region 103.

The formed flexible substrate 100 may be positioned in the first andsecond serve chambers SC1 and SC2 respectively having the first andsecond residual gas analyzers RGA1 and RGA2, and whether the firstreactant 41 has infiltrated into the inside of chambers may beidentified, and then, formation of the first barrier region 103 may beidentified.

The flexible substrates 100 and 100′ according to an exemplaryembodiment of the present invention may be applicable in various areas.Below, a case in which the flexible substrates 100 and 100′ are employedin a display apparatus having the bending area will be described in moredetail as an example. However, the flexible substrates 100 and 100′ maybe employed in a foldable or rollable display apparatus or a displayapparatus without a bending area.

A display apparatus may be an apparatus displaying an image, and mayinclude a liquid crystal display, an electrophoretic display, an organiclight-emitting display, an inorganic light-emitting display, a fieldemission display, a surface-conduction electron-emitter display, aplasma display, or a cathode ray display.

Below, a display apparatus according to an exemplary embodiment of thepresent invention will be described in more detail with the organiclight-emitting display as an example. However, a display apparatusaccording to exemplary embodiments of the present invention is notlimited thereto and various display apparatuses may include the flexiblesubstrates according exemplary embodiments of the present invention.

FIG. 9 is a perspective view of a portion of a display apparatusaccording to an exemplary embodiment of the present invention. FIG. 10is a cross-sectional view of a portion of the display apparatus of FIG.9. According to an exemplary embodiment of the present invention, aportion of a flexible substrate 100 included in the display apparatusmay have a bent shape and thus, a portion of the display apparatus mayhave substantially a same bent shape as the flexible substrate 100.However, the display apparatus described with reference to FIGS. 9 and10 is illustrated in an un-bent state in FIG. 10.

Referring to FIGS. 9 and 10, the flexible substrate 100 included in thedisplay apparatus according to an exemplary embodiment of the presentinvention may be divided into a display area DA in which a displaydevice is positioned for displaying an image and a non-display areaaround the display area DA. The non-display area may include a bendingarea BA which is bent around a bending axis BAX as a center bendingaxis. The bending area BA may refer to an area having a radius ofcurvature after bending.

The bending area BA may extend in a first direction (+y direction) andbe between a first area 1A and a second area 2A in a second direction(+x direction) crossing the first direction. The flexible substrate 100may be bent along a bending axis BAX, which extends in the firstdirection (+y direction), as a center.

The flexible substrate 100 may include the first barrier region 103, andthus moisture and oxygen, which may enter from the outside, may bereduced or prevented from infiltrating into a display device 300. Thefirst barrier region 103 may be positioned, at least in part, in theneutral plane NP of the flexible substrate 100. Thus, even when theflexible substrate 100 is bent in the bending area BA, the crackoccurrence in the first barrier region 103 may be reduced or prevented.

The first area 1A may include the display area DA. The first area 1A mayinclude a portion of the non-display area in addition to the displayarea DA. The second area 2A may also include the non-display area. Thebending area BA and/or the second area 2A may also include the displayarea DA.

A plurality of pixels may display an image in the display area DA of theflexible substrate 100. Elements such as a thin film transistor (TFT)210, an organic light-emitting diode (OLED), and a capacitor (Cst) maybe in the display area DA.

The display area DA may include a gate line transmitting a gate signal,a data line transmitting a data signal, a driving power linetransmitting power, and a common power line. The display area mayinclude a first signal wire 213 b. The pixel may be configured todisplay the image via electrical signals provided from the TFT, the Cst,and the OLED, which are connected to the gate line, the data line, andthe driving power line. The pixel P may emit light at a brightnesscorresponding to a driving current passing through the OLED in responseto the data signal according to a driving power supplied to the pixeland the common power. The first signal wire 213 b may be connected to adriving circuit unit via a fan-out wire 720 a. The pixel may include aplurality of pixels P, which may be arranged in various shapes such as astripe array and a PenTile array.

The fan-out wire 720 a may be in the non-display area and may beconnected to the first signal wire 213 b applying an electrical signalto the TFT 210 or the display device 300 in the display area DA. Thefirst signal wire 213 b may correspond to various wires in the displayarea DA, such as the gate line GL, the data line DL, the driving powerline, and the common power line. The fan-out wire 720 a may be connectedto the first signal wire 213 b and a portion thereof may be in thebending area BA. In an exemplary embodiment of the present invention,the fan-out wire 720 a may extend from the first area 1A to a portion ofthe bending area BA or to the second area 2A through the bending areaBA.

The display device 300 may include the OLED in the display area DA. TheOLED may be electrically connected to the TFT 210 and thus a pixelelectrode 310 may be electrically connected to the TFT 210. A thin filmtransistor (TFT) may be in a peripheral area outside the display area DAof the flexible substrate 100. The TFT in the peripheral area may be,for example, a portion of a circuit unit for controlling an electricalsignal applied to the display area DA.

The TFT 210 may include a semiconductor layer 211, a gate electrode 213,a source electrode 215 a, and a drain electrode 215 b, which may eachinclude amorphous silicon, polycrystalline silicon, oxide semiconductoror organic semiconductor materials.

The gate electrode 213 may be connected to a gate wire which provides anon/off signal to the TFT 210 and may include a relatively low-resistancemetal material. For example, the gate electrode 213 may have asingle-layer or a multi-layer structure. Each layer may include at leastone conductive material, such as, molybdenum (Mo), aluminum (Al), copper(Cu) and/or titanium (Ti).

The source electrode 215 a and the drain electrode 215 b may have asingle-layer or a multi-layer structure having relatively highconductivity. The source electrode 215 a and the drain electrode 215 bmay be respectively connected to a source area and a drain area of thesemiconductor layer 211. For example, the source electrode 215 a and thedrain electrode 215 b may have a single-layer or a multi-layerstructure. Each layer may include at least one conductive material, suchas, Al, Cu and/or Ti.

The TFT 210 according to an exemplary embodiment of the presentinvention may be a top gate type TFT in which the gate electrode 213 isabove the semiconductor layer 211, but exemplary embodiments of thepresent invention are not limited thereto. The TFT 210 according to anexemplary embodiment of the present invention may be a bottom gate typeTFT in which the gate electrode 213 is under the semiconductor layer211.

A gate insulating layer 120 including inorganic materials such assilicon oxide, silicon nitride, and/or silicon oxynitride for securinginsulation between the semiconductor layer 211 and the gate electrode213 may be between the semiconductor layer 211 and the gate electrode213. An interlayer insulating layer 130 including inorganic materialssuch as silicon oxide, silicon nitride, and/or silicon oxynitride may beon the gate electrode 213, and the source electrode 215 a and the drainelectrode 215 b may be on the interlayer insulating layer 130.Insulating layers including inorganic materials may be formed via theCVD or ALD.

A buffer layer 110 including inorganic materials such as silicon oxide,silicon nitride, and/or silicon oxynitride may be between the TFT 210and the flexible substrate 100. The buffer layer 110 may increaseflatness of a top surface of the flexible substrate 100, and may preventor reduce infiltration of impurities from the flexible substrate 100 tothe semiconductor layer 211 of the TFT 210. The buffer layer 110 mayhave a single-layer or multi-layer structure.

A planarization layer 140 may be on the TFT 210. For example, when theOLED is above the TFT 210, the planarization layer 140 may planarize atop surface of a protection layer covering the TFT 210. Theplanarization layer 140 may include, for example, organic materials suchas PI, acryl, benzocyclobutene (BCB), or hexamethyldisiloxane (HMDSO).The planarization layer 140 may have a single-layer structure; however,the planarization layer 140 may be variously modified. For example, theplanarization layer 140 may have a multi-layer structure.

The OLED may include the pixel electrode 310, a counter electrode 330,and an intermediate layer 320. The intermediate layer may be between thepixel electrode 310 and the counter electrode 330. The OLED my includean organic light-emitting layer, and may be on the planarization layer140, in the display area DA of the flexible substrate 100. The pixelelectrode 310 may contact any one of the source electrode 215 a and thedrain electrode 215 b via an opening OP1 formed in the planarizationlayer 140. The pixel electrode 310 may be electrically connected to theTFT 210.

A pixel definition layer 150 may be on the planarization layer 140. Thepixel definition layer 150 may define a pixel by having an openingcorresponding to respective sub-pixels. The opening may expose at leasta central portion of the pixel electrode 310. The pixel definition layer150 may reduce or prevent an occurrence of an arc on edges of the pixelelectrode 310 by increasing a distance between edges of the pixelelectrode 310 and the counter electrode 330 above the pixel electrode310. The pixel definition layer 150 may include, for example, organicmaterials such as PI, acryl, BCB or HMDSO.

The intermediate layer 320 of the OLED may include one or morerelatively low molecular weight materials or polymer materials. When theintermediate layer 320 includes low molecular weight materials, a holeinjection layer (HIL), a hole transport layer (HTL), an emission layer(EML), an electron transport layer (ETL), and/or an electron injectionlayer (EIL) may have laminated structures with a single-layer ormultiple layers, and may include various organic materials such ascopper phthalocyanine (CuPc),N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), ortris(8-hydroxyquinoline) aluminum (Alq3). The above-described layers maybe formed via a vacuum deposition method.

When the intermediate layer 320 includes polymer materials, theintermediate layer 320 may have a structure which includes an HTL and anEML. As an example, the HTL may include poly 3,4-ethylenedioxythiophene(PEDOT) and the light-emitting layer may include relatively highmolecular weight (e.g., polymer) materials such aspoly-phenylenevinylene (PPV) and polyfluorene. The intermediate layer320 may be formed via screen printing, inkjet printing, or laser inducedthermal imaging (LITI). However, exemplary embodiments of the presentinvention are not limited thereto, and the intermediate layer 320 mayhave various other structures. As an example, the intermediate layer 320may include an integrated layer disposed on a plurality of pixelelectrodes 310 and may include a patterned layer corresponding to eachof the plurality of pixel electrodes 310.

The counter electrode 330 may be on a top portion of the display area DAand may cover the display area DA. As an example, the counter electrode330 may have an integrated structure including a plurality of OLEDs andthus, may correspond to the plurality of pixel electrodes 310.

The OLED may be damaged by humidity, or oxygen from outside the OLED. Anencapsulation layer 400 may protect the OLEDs by encapsulating theOLEDs. The encapsulation layer 400 may cover the display area DA andextend to the outside of the display area DA. The encapsulation layer400 may include a first inorganic encapsulation layer 410, an organicencapsulation layer 420, and a second inorganic encapsulation layer 430.

The first inorganic encapsulation layer 410 may cover the counterelectrode 330, and may include silicon oxide, silicon nitride, and/orsilicon oxynitride. Other layers such as a capping layer may be betweenthe first inorganic encapsulation layer 410 and the counter electrode330. The first inorganic encapsulation layer 410 may take on a shape ofan underlying structure, and thus a top surface of the first inorganicencapsulation layer 410 need not be flat. The organic encapsulationlayer 420 may cover the first inorganic encapsulation layer 410, and atop surface thereof may be generally smooth. As an example, the topsurface of the organic encapsulation layer 420 may be substantially flatin an area corresponding to the display area DA. The organicencapsulation layer 420 may include at least one material, such as, PET,PEN, PC, PI, PES, polyoxymethylene (POM), polyallylate, or HMDSO. Thesecond inorganic encapsulation layer 430 may cover the organicencapsulation layer 420, and may include silicon oxide, silicon nitride,and/or silicon oxynitride. The second inorganic encapsulation layer 430may prevent the organic encapsulation layer 420 from being exposed tothe outside by contacting the first inorganic encapsulation layer 410 atan edge outside the display area DA.

Since the encapsulation layer 400 includes the first inorganicencapsulation layer 410, the organic encapsulation layer 420, and thesecond encapsulation layer 430, even when a crack occurs in theencapsulation layer 400, the crack need not be connected between thefirst inorganic encapsulation layer 410 and the organic encapsulationlayer 420 or between the organic encapsulation layer 420 and the secondencapsulation layer 430. Thus, the formation of an infiltration route ofhumidity or oxygen from the outside to the display area DA may beprevented or reduced.

A touch electrode 710 may be above the encapsulation layer 400, and acover layer 730 protecting the touch electrode 710 may be on the touchelectrode 710.

The touch electrode 710 may be connected to a touch wire 720 fortransmitting a signal therefrom, and the touch wire 720 may extend tothe non-display area from above the encapsulation layer 400 along an endsurface of the encapsulation layer 400. The touch wire 720 may beconnected to the touch electrode 710 and at least a portion thereof mayextend from above the encapsulation layer 400 to be in the bending areaBA. According to an exemplary embodiment of the present invention, thetouch wire 720 may extend through the bending area BA. The touch wire720 may extend from above the encapsulation layer 400 along an endsurface of the encapsulation layer 400, and in this case, the endsurface of the encapsulation layer 400 may include curves. The curvesmay be formed by forming steps between the planarization layer 140 andthe pixel definition layer 150. The touch wire 720 may extend to thenon-display area with gradual slopes from above the encapsulation layer400 via the curves.

The touch electrode 710 and the touch wire 720 may have a single-layeror a multi-layer structure. Each layer may include at least one materialthat is relatively highly conductive. For example, the touch electrode710 and the touch wire 720 may include a single-layer or multiple layersincluding conductive materials, such as Al, Cu and/or Ti. The touchelectrode 710 may include the same material as the touch wire 720.

The cover layer 730 may be flexible, and may include polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS), PI, acrylate, PET, orPEN. The cover layer 730 may extend to the non-display area and coverthe fan-out wire 720 a. Thus, the cover layer 730 may protect both atouch electrode 710 and the fan-out wire 720 a. The cover layer 730 mayextend from the display area DA to at least the bending area BA.

A touch buffer layer 610 may be between the encapsulation layer 400 andthe touch screen layer 700. The touch buffer layer 610 may protect theencapsulation layer 400 and may block an interference signal which canoccur during an operation of the touch screen layer 700. The touchbuffer layer 610 may include inorganic materials such as silicon oxide,silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride,titanium oxide, or titanium nitride, or organic materials such as PI,polyester or acryl, and may include a laminated layer including one ormore of the materials described above.

The touch buffer layer 610 may be directly formed on the encapsulationlayer 400 via a deposition process. Since the touch screen layer 700 mayalso be directly formed on the touch buffer layer 610, a separateadhesive layer may be omitted on the encapsulation layer 400. Thus, athickness of the display apparatus may be reduced.

The non-display area may include the bending area BA. The fan-out wire720a crossing the bending area BA may be included in the non-displayarea. The fan-out wire 720 a may be electrically connected to first,second, and third signal wires 213 b, 213 c, and 215 c which may applyelectrical signals to the TFT 210 or the display device 300 in thedisplay area DA. The fan-out wire 720 a and the first, second, and thirdsignal wires 213 b, 213c, and 215 c may be electrically connected toeach other may and may the fan-out wire 720 a directly connected to thefirst signal wire 213 b via a contact hole as well as the fan-out wire720 a indirectly connected to the second or third signal wire 213 c or215 c.

The first signal wire 213 b may be electrically connected to the secondor third signal wire 213 c or 215 c in the display area DA. According toan exemplary embodiment of the present invention, the second or thirdsignal wire 213 c or 215 c may be the gate line applying a signal to thegate electrode 213. According to an exemplary embodiment of the presentinvention, the second or third signal wire 213 c or 215 c may be thedata line applying a signal to the source electrode 215 a or the drainelectrode 215 b. According to an exemplary embodiment of the presentinvention, the first signal wire 213 b may be connected to the secondsignal wire 213 c via a via hole.

According to an exemplary embodiment of the present invention, the firstand second signal wires 213 b and 213 c may include a same material asthe gate electrode 213. The third signal wire 215 c may include a samematerial as the source electrode 215 a and the drain electrode 215 b.According to an exemplary embodiment of the present invention, thefan-out wire 720 a may include a same material as the third signal wire215c. Alternatively, the fan-out wire 720 a may include a same materialas the touch wire 720.

An organic material layer 160 may be in at least a portion of a spacebetween the fan-out wire 720 a and the flexible substrate 100 in thebending area BA. When the display apparatus is subject to bending, theorganic material layer 160 may reduce or prevent an occurrence of cracksin the fan-out wire 720 a in the bending area BA. The organic materiallayer 160 may absorb tensile stress caused by bending in the flexiblesubstrate 100 and may reduce a concentration of tensile stress in thefan-out wire 720 a.

The organic material layer 160 may be substantially simultaneouslyformed with the planarization layer 140 or the pixel definition layer150, and may include a same material as the planarization layer 140and/or the pixel definition layer 150. As an example, the organicmaterial layer 160 may be substantially simultaneously formed in a maskprocess for forming the planarization layer 140 or the pixel definitionlayer 150 and thus, a separate mask process for forming the organicmaterial layer 160 may be omitted.

The buffer layer 110, the gate insulating layer 120 and the interlayerinsulating layer 130 may be collectively referred to as an inorganicinsulating layer. The inorganic insulating layer may include an openingin a position corresponding to the bending area BA. As an example, thebuffer layer 110, the gate insulating layer 120 and the interlayerinsulating layer 130 may respectively include openings 110 a, 120 a, and130 a corresponding to the bending area BA. The openings correspondingto the bending area BA may be referred to as the openings overlappingthe bending area BA. An area of each of the openings may be larger thanthat of the bending area BA. As an example, a width of an opening OW maybe greater than a width of the bending area BA. The area of the openingsmay be defined as the area of the opening with the smallest area amongthe openings 110 a, 120 a, and 130 a of the buffer layer 110, the gateinsulating layer 120, and the interlayer insulating layer 130. As anexample, the area of the opening may be defined as the area of theopening 110 a of the buffer layer 110.

The display apparatus according to an exemplary embodiment of thepresent invention may include the organic material layer 160 filling atleast a portion of openings of the inorganic material layer. As anexample, the organic material layer 160 may fill all of the openings.The fan-out wire 720 a may extend from the first area 1A to the secondarea 2A through the bending area BA. The fan-out wire may be on theorganic material layer 160. The fan-out wire 720 a may be on theinorganic material layer, including the interlayer insulating layer 130,when the organic material layer 160 is omitted.

Since a hardness of the inorganic insulating layer may be higher thanthat of the organic material layer 160, a probability of the crackoccurrence in the inorganic insulating layer in the bending area BA maybe relatively high. When a crack occurs in the inorganic insulatinglayer, a probability that the crack propagates up to the fan-out wire720 a may be relatively high. Thus, the propagation of the crack may beblocked by the organic material 160. However, the probability of thecrack occurrence in the inorganic material layer may be further reducedby forming the openings in the inorganic insulating layer. Thus, theconcentration of tensile stress in the fan-out wire 720 a may bereduced.

Referring to FIG. 10, the organic material layer 160 may cover an insidesurface of the openings of the inorganic material layer. A conductivematerial layer may be formed on substantially the entire surface of theflexible substrate 100. The conductive material layer may be patternedto form various wires. When the organic material layer 160 does notcover the inside surface of the opening 110 a of the buffer layer 110,the inside surface of the opening 120 a of the gate insulating layer120, or the inside surface of the opening 130 a of the interlayerinsulating layer 130, during a process of patterning the conductivematerial layer, the conductive material need not be removed from theinside surface of the opening 110 a of the buffer layer 110, the insidesurface of the opening 120 a of the gate insulating layer 120, or theinside surface of the opening 130 a of the interlayer insulating layer130. In this case, the remaining conductive material may cause a shortbetween other conductive layers. Thus, when the organic material layer160 is formed, the organic material layer 160 may cover the insidesurfaces of openings of the inorganic material layer. The organicmaterial layer 160 may have a substantially uniform thickness; however,exemplary embodiments of the present invention are not limited thereto.As an example, the organic material layer 160 may have a differentthickness depending on locations such that the organic material layer160 may have the top surface thereof with a gradual curve slope near theinside surface of the opening 110 a of the buffer layer 110, the insidesurface of the opening 120 a of the gate insulating layer 120, or theinside surface of the opening 130 a of the interlayer insulating layer130.

The display apparatus according to an exemplary embodiment of thepresent invention may employ the flexible substrate 100 having the firstbarrier region 103 and thus, outside air, moisture and oxygen which caninfiltrate from below the flexible substrate 100 may be reduced orprevented from infiltrating into the inside of the display area. Thefirst barrier region 103 of the flexible substrate 100 may be on theneutral plane NP of the flexible substrate 100 and thus, when theflexible substrate 100 is bent in the bending area BA, a crackoccurrence in the first barrier region 103 may be reduced or prevented.

It should be understood that embodiments described herein should beconsidered in a descriptive sense and not for purposes of limitation.Descriptions of features or aspects within each embodiment shouldtypically be considered as available for other similar features oraspects in other embodiments.

While one or more embodiments have been described with reference to thefigures, it will be understood by one of ordinary skill in the art thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the present invention.

What is claimed is:
 1. A flexible substrate comprising: a polymersubstrate; a first barrier region, wherein at least a portion of thefirst barrier region is formed on a neutral plane of the polymersubstrate; a top region formed above the first barrier region; and abottom region formed below the first barrier region, wherein the firstbarrier region comprises a first inorganic material disposed in at leasta portion of a free volume of the polymer substrate, and wherein adensity of the first inorganic material in the first barrier region isgreater than a density of the first inorganic material in the top orbottom regions.
 2. The flexible substrate of claim 1, wherein thedensity of the first inorganic material in the first barrier regiongradually decreases from a center thickness of the first barrier regiontoward upper and lower surfaces of the polymer substrate.
 3. Theflexible substrate of claim 1, wherein the first inorganic materialcomprises at least one of silicon nitride, aluminum nitride, zirconiumnitride, titanium nitride, hafnium nitride, tantalum nitride, siliconoxide, aluminum oxide, titanium oxide, tin oxide, serium oxide, orsilicon oxynitride (SiON).
 4. The flexible substrate of claim 1, whereinthe first inorganic material of the first barrier region fills fromabout 0.1% to about 50% of a free volume of the first barrier region,and wherein an average thickness of the first barrier region is equal toor less than from about 5% to about 50% of a thickness of the polymersubstrate.
 5. The flexible substrate of claim 1, wherein a position of abasic core of the first barrier region does not coincide with a positionof the neutral plane.
 6. The flexible substrate of claim 1, wherein athickness of the polymer substrate is from about 10 m to about 100 μm,and wherein an average thickness of the first barrier region is fromabout 50 nm to about 50 μm.
 7. The flexible substrate of claim 1,further comprising a second barrier region in at least one of the topand bottom regions, wherein the second barrier region comprises a secondinorganic material disposed in at least a portion of the free volume ofthe polymer substrate, and wherein a volume of the second barrier regionis less than the volume of the first barrier region.
 8. The flexiblesubstrate of claim 7, wherein the second inorganic material is the sameas the first inorganic material.
 9. The flexible substrate of claim 1,wherein a hardness of the first barrier region is greater than ahardness of the top and bottom regions.
 10. A method of manufacturing aflexible substrate, the method comprising: injecting a first reactantabove a polymer substrate into a top surface of the polymer substrateand infiltrating the first reactant into the polymer substrate;injecting a second reactant below the polymer substrate into a bottomsurface of the polymer substrate and infiltrating the second reactantinto the polymer substrate; and forming a barrier region by filling atleast a portion of a free volume of the polymer substrate with aninorganic material formed via a reaction of the first and secondreactants inside the polymer substrate.
 11. The method of claim 10,further comprising, after the forming of the barrier region, identifyingwhether at least one of the first and second reactants has penetratedinto the polymer substrate.
 12. The method of claim 10, wherein, in theinfiltrating of the first reactant, a pressure above the polymersubstrate is greater than a pressure below the polymer substrate. 13.The method of claim 10, wherein, in the infiltrating of the secondreactant, a pressure above the polymer substrate is less than a pressurebelow the polymer substrate.
 14. The method of claim 10, wherein theinfiltrating of the first reactant and the infiltrating of the secondreactant are sequentially performed.
 15. The method of claim 10, whereinthe first reactant is one of water (H₂O), ozone (O₃), or ammonia (NH₃).16. The method of claim 10, wherein the inorganic material formed viathe reaction of the first and second reactants comprises at least one ofsilicon nitride, aluminum nitride, zirconium nitride, titanium nitride,hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide,titanium oxide, tin oxide, serium oxide, or SiON.
 17. The method ofclaim 10, wherein at least a portion of the barrier region is on aneutral plane of the polymer substrate.
 18. The method of claim 10,wherein a manufacturing apparatus configured to manufacture the flexiblesubstrate comprises a first serve chamber and a second serve chamber,wherein the polymer substrate is disposed between side walls of thefirst and second serve chambers, and wherein the polymer substrate formsan airtight seal in the first and second chambers, the first servechamber comprises a first gas supplier configured to supply the firstreactant, a first residual gas analyzer, and a first temperaturecontroller, and the second serve chamber comprises a second gas supplierconfigured to supply the second reactant, a second residual gasanalyzer, and a second temperature controller.
 19. A method ofmanufacturing a flexible substrate, the method comprising: Infiltratinga first reactant into substantially an entire polymer substrate;removing the first reactant infiltrated into a top region in the polymersubstrate; infiltrating a second reactant into at least a portion of thepolymer substrate; and forming a barrier region by filling at least aportion of a free volume of the polymer substrate with an inorganicmaterial formed via a reaction of the first and second reactants insidethe polymer substrate.
 20. The method of claim 19, wherein theinfiltrating of the first reactant is performed after the polymersubstrate was placed in an oven including the first reactant.
 21. Themethod of claim 19, wherein the removing of the first reactant isperformed by applying heat to a top surface of the polymer substrate anddiffusing the first reactant to outside the polymer substrate.
 22. Themethod of claim 19, wherein the infiltrating of the second reactant isperformed inside a vacuum chamber device.
 23. The method of claim 19,wherein the first reactant is one of H₂O, O₃, or NH₃.
 24. The method ofclaim 19, wherein the inorganic material formed via the reaction of thefirst and second reactants comprises at least one of silicon nitride,aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride,tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tinoxide, serium oxide, or SiON.
 25. The method of claim 19, wherein atleast a portion of the barrier region is on a neutral plane of thepolymer substrate.
 26. The method of claim 19, further comprising, afterthe forming of the barrier regions, identifying whether at least one ofthe first and second reactants penetrated through the polymer substrate.27. A display apparatus comprising: a flexible substrate including adisplay area and a non-display area; a display device in the displayarea and a thin film transistor connected to the display device; and anencapsulation layer configured to encapsulate the display area, whereinthe flexible substrate comprises: a polymer substrate; a first barrierregion, wherein at least a portion of the first barrier region is formedon a neutral plane of the polymer substrate; a top region formed abovethe first barrier region; and a bottom region formed below the firstbarrier region, wherein the first barrier region comprises a firstinorganic material disposed in at least a portion of a free volume ofthe polymer substrate, and wherein a density of the first inorganicmaterial in the first barrier region is greater than a density of thefirst inorganic material in the top or bottom regions.
 28. The displayapparatus of claim 27, wherein the non-display area of the flexiblesubstrate comprises a bending area bent around a bending axis, thedisplay apparatus further comprising: a fan-out wire, wherein at least aportion of the fan-out area is in the bending area; and an organicmaterial layer, wherein at least a portion of the organic material layeris between the fan-out wire and the flexible substrate in the bendingarea.
 29. The display apparatus of claim 28, further comprising aninorganic insulating layer on the flexible substrate, the inorganicinsulating layer having an opening corresponding to the bending area,wherein the organic material layer fills at least a portion of theopening.
 30. The display apparatus of claim 27, wherein the displaydevice is an organic light-emitting diode comprising a pixel electrode,a counter electrode facing the pixel electrode, and an intermediatelayer including an organic light-emitting layer between the pixelelectrode and the counter electrode.
 31. The display apparatus of claim27, wherein a density of the first inorganic material in the firstbarrier region gradually decreases from a center thickness of the firstbarrier region toward upper and lower ends of the flexible substrate.32. The display apparatus of claim 27, wherein a thickness of the topregion is different from a thickness of the bottom region.
 33. Thedisplay apparatus of claim 27, further comprising a second barrierregion in at least one of the top and bottom regions, wherein the secondbarrier region comprises a second inorganic material disposed in atleast a portion of the free volume of the polymer substrate, and whereina volume of the second barrier region is less than a volume of the firstbarrier region.
 34. A polymer substrate, comprising: a bottom region; atop region; and a first barrier region formed between the bottom regionand the top region, wherein the first barrier region comprises a firstinorganic material disposed in at least a portion of a free volume ofthe polymer substrate, wherein a density of the first barrier region isgreater than densities of the bottom region and the top region, andwherein densities of bottom region, the first barrier region and the topregion gradually decreases from the first barrier region toward a lowersurface of the bottom region and an upper surface of the top region. 35.The polymer substrate of claim 34, further comprising a second barrierregion in at least one of the top and bottom regions.